Heretofore, oxygen has been generated commercially by fractionalization and cryogenic processes, and then stored in cylinders that are delivered to end users. More recently, however, oxygen generators have been used to produce on-site oxygen, as an alternative to the supply of storage cylinders. Depending on usage, such oxygen generators may provide oxygen at a lower cost then that afforded by the cylinders.
Air is about 21% oxygen and about 78% nitrogen. It is known that an appropriate molecular sieve (e.g., containing zeolite or equivalent) will selectively adsorb nitrogen from a flow of air passing therethrough. The result is a flow of oxygen-rich gas. Thus, pressure swing adsorption-type oxygen generators have been developed to provide a continuous flow of compressed air through a zeolite bed to adsorb nitrogen from the gas and to provide an oxygen-rich fluid stream. Typically, the apparatus contains two zeolite beds, such that one may be desorbed of its accumulated nitrogen by a reverse flow, while the other is providing an oxygen-rich gas in a forward flow.
However, there are some applications that require a smaller amount of oxygen. For example, it has been proposed to enhance water coolers by providing a flow of oxygen to the chilled water. In addition to this, application such as hot tubs, furnaces and the like may require a lower flow of oxygen.